Preliminary experiments on effects of microwave irradiation (1 mWatts/cm2) on barbiturate induction time and sleeping time in mice indicate the following interactions. Barbital and phenobarbital induction times were shortened by irradiating for 10 minutes immediately before intravenous administration of the barbiturate. The second distinct interaction seen was that the sleeping time to these two barbiturates were prolonged. Sleeping times to hexobarbital and pentobarbital were less affected. Since it is the long acting barbiturates (where metabolism is not as important a factor in terminating drug action) which were affected more by irradiation and the shorter acting barbiturates which penetrate into the central nervous system quickly (and are the ones where metabolism is important in terminating action) were not affected as much, the working hypothesis is that microwave irradiation increased blood brain permeability. Another separate effect was manifested when mice which were already asleep from phenobarbital were continuously irradiated. These mice regained their righting reflex. This separate effect appears to be an analeptic effect. Another indication of microwave irradiation increasing blood brain barrier permeability was indicated by the increased mortality seen in Japanese Encephalitis Virus (JEV). Two days after innoculation with JEV, mice irradiated with 1 mWatt/cm2 for 5 min showed increase neurotropic mortality to JEV. This irradiation dosage was well below that which caused any lethality by itself. In the coming year, the experiments will be aimed toward substantiatig the postulated increase in blood brain permeability. This will be examined by determining time dependent brain concentrations of the barbiturates and the increased presence of JEV in the brain.